Automatically adjusting brake



May 31 1938- J. J-DENHAM 2,119,384

AUTOMATICALLY ADJUSTING BRAKE Fivled Aug. 1l, 1936 ATTORNEY.

Patented "May 31,1938

` UNITED sTATEs PATENT OFFICE AUTOMATICALLY ADJUSTING BRAKE John J. Denham, Berkeley, Calif., assigner to Albert E. Jura, Berkeley, Calif... doing business as Shand & Jura Company` l Application August ll, 1936, Serial No. 95,367

3 Claims. (Cl. 188-'l9.5)

This invention relates. generally to the conlocated in positions adjacent the free ends of struction of brakes, such as are suitable for autothe brake shoes. 'Ihe representative form of motive vehicles. It applies particularly to brakes mounting for each cam 2|, illustrated in Fig. t2, incorporating automatic take-up means, to com consists of a stud 22, ycarried by the backing 5 pensate for wear upon the brake lining. plate Il. Cam 2| is jcurnalled upon the innerl 5 It is an object of the invention to provide an end of stud 22, for relative angular adjustments. improved brake of the above character, which Suitable frictioning means is interposed between will have a minimum number of working parts, each cam 2| and its associated stud 22, whereby and which will afford a high degree of reliability for ordinary road shocks to which the brake may in carrying out its desired functions. be subjected, the cam will maintain a iixed 1o Another object of the invention is to provide position. For example a pair of thrust washers an improved automatic take-up means particu- 2l and 24 are shown, with the washer 23 seated larly suited for use with hydraulic brakes oi the upon stud 22, andwasher 24 engaging one side internal type. oi cam 2|. Interposed between these thrust i5 Further objects of the invention will appear washers there is a spring washer 2t, which is l5 from the following description in which the prenormally compressed within its elastic limit. ferred embodiment of the invention has been Formed upon the web I4 of each shoe there set forth in detail in conjunction with the acis a lug 2l, the face 2l of which is adapted to COmDanying drawing: engage the peripheral surface 29, of the cam 2|. zo Referring to the drawing: It is the engagement or abutment between these Fig. l is a cross-sectional view in side elevasurfaces which determines the released positions tion, showing the interior of a brake incorporatof the two shoes, and it will be evident that being the present invention. cause of the contour of the cam surfaces 2l, Fig. 2 is a cross-sectional detail taken along which are eccentric with respect to the centers 25 the line 2--2 of Fig. l. l of studs 22, a change in the angular setting of g5 That form of the inventionillustrated in the the two cams will serve to adjust or vary the drawing consists of a brake drum Il, together released positions of the two shoes. with a conventional cover or backing plate Il. In order to automatically adjust the angular As applied to automotive vehicles, the drum I0 setting of the two cams, when the shoes are is secured to or forms a part of the wheel, while actuated to braking positions, I provide simple 3o the backing plate Il is secured to the vehicle. means acting directly between each cam and its Within the brake drum I0 are the two arcuatel associated shoe. Thus each shoe is provided or segmental brake shoes l2, each of which is with a lug or extension arm 30, into which a provided with the usual lining I3, formed 0f set screw 3| is threaded. The end of set screw fabric or molded material. In conformance with 3i is adapted to engage the face of a lug or 35 conventional designs the body of each shoe inarm 32, which is xed to the associated cam 2l. cludes a web I4, to ail'ord proper structural Operation of the brake described above, can Strength. be briefly outlined as followsz-At the time the The mounting for the shoes, in order to enable brake is assembled, which may follow applica- 40 their movement between braking and released tion of new linings to the shoes, the cams 2l 40 positions, includes pivotal connections Ii to the are adjusted to such angular positions as to give backing plate il. Interposed between the free a proper amount of clearance between the brake ends of the shoes there is a suitable hydraulic lining I3 and the inner peripheral surface'of motive unit I1, which can consist of a cylinder the drum l0. After this adjustment has been and a pair of pistons engaging the adjacent ends ,made there should be sufficient clearance be- 45 of the shoes. The cylinder is shown connected tween the ends of set screws 3| and the coto a hose I8,`which leads to a suitable hydraulic operating faces of arms 32, so that the shoes actuator for applying liquid under pressure. A canbeforced to braking position, without causing tenSiOrl Spring I9 iS ShOWn intercgnecting the a change in the angular setting of the cam. In

free ends of the shoes, whereby th'e shoes are other words for braking positions of the shoes, 50 moved to released positions, after hydraulic presset screws 3| should just come into engagement Sure applied t0 hOSe IB iS relieved. with the arms 32. As the brake linings become The automatic take-up mechanism which I more compressed or wear away in usage, the employ with the parts described above, can be brake shoes will be forced into closer proximity ISIS.` constructed as followsz-A pair of cams 2l are to the inner peripheral surface of the drum, in 56 moving to braking positions. Such movement will cause the set screws 3l to engage and move arms 32, to changethe angular setting of cams 2l by compensating amounts. A change in the setting of cams 2| causes the brake shoes to stop in a different position when released, so that in effect the clearance between the brake lining and the inner periphery of the drum, remains substantially constant. With aconventional type of pedal operated hydraulic actuator, connected to the hydraulic cylinder unit i1, it will be evident that the automatic take-up thus afforded will automatically maintain the pedal movement substantially constant, throughout the life of the brake lining.

It will be evident that my brake utilizes a minimum number of working parts, thus facili- '-tating manufacture and assembly. Assembly and adjustments of my brake can be readily made by ordinary garage mechanics, and after being properly adjusted, the brake will afford long reliable service without further manual attention.

I claim:

1. A brake comprising a brake drum, a backing plate associated with the drum, at least two segmental brake shoes, corresponding ends oi' said shoes being pivotally secured to the backing plate, a hydraulic motive unit connected to the free ends of said shoes and serving to actuate the same to braking positions, spring means for urging the free ends of said shoes together and towards released positions, a pair of cam elements movably carried by the backing plate and forming adjustable abutments for the released positions of said braking shoes, and means for determining the settings of said cam elements, when the shoes are moved to braking positions, said last means comprising lugs formed in said cam elements and adjustable members carried by the shoes and adapted to engage said lugs.

2. A brake comprising a brake drum, a backing plate associated with the drum, a brake shoe mounted upon the backing plate and movable between braking and released positions, means for actuating the shoe between braking and released positions, and automatic take-up means for the shoe, said means comprising a single angulariy movable cam element mounted upon the backing plate, said cam element forming an adjustable abutment for determining the released position of the shoe, there being sulcient friction against angular movement between the cam element and said backing plate whereby said cam element normally maintains a fixed position with respect to the backing plate, and adjustable means for determining the setting of said cam element when the shoe is actuated tobraking position, adjustment of said means serving to vary the amplitude of movement of the shoe in moving between braking and released positions.

3. A brake comprising a brake drum, a backing plate associated with the drum, a brake shoe mounted upon the backing plate and movable between braking and released positions, means for actuating the shoe between braking and released positions, and automatic take-up means for the shoe, said means comprising a single angularly movable cam element mounted upon the backing plate, said cam element forming an adjustable abutment for determining the released position of the shoe, there being suiiicient friction against angular movement between the cam element and said backing plate whereby said cam element normally maintains a fixed position with respect to the backing plate, and means for determining the setting of said cam element when the shoe is actuated to braking position, said last means comprising a shoulder on the cam element and a member adjustably carried by the shoe and adapted to engage said shoulder.

JOHN J. DENHAM. 

